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MANUAL.txt
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127 lines (98 loc) · 5.36 KB
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_____________________________________________________________
CCCC PPPPP LL AAAA PPPPP !!
CC CC PP PP LL AA AA PP PP !!
CC PP PP LL AA AA PP PP !!
CC PPPPP LL AAAAAA PPPPP !!
CC CC PP LL AA AA PP
CCCC PP LLLLLL AA AA PP !!
_____________________________________________________________
Chemical Potential Limits Analysis Program
_____________________________________________________________
Version 1.1 2013
John Buckeridge (j.buckeridge@ucl.ac.uk)
_____________________________________________________________
CPLAP is a program designed to determine the thermodynamical
stability of a material, and, if it is stable, to determine
the ranges of the constituent elements' chemical potentials
within which it is stable, in comparison with competing phases
and the elemental forms.
Before running CPLAP, the energies of the material and all its
competing phases (search the chemical database extensively for
this) must be calculated. Use the same level theory for every
calculation, and use the same units when inputting to CPLAP.
The chemical potentials are defined with respect to the
energy of the species in their elemental form. So the zero of
chemical potential for a species is the energy per atom of
that species in its elemental form.
**************************************************************
COMPILATION
Just type 'make'.
You can set your preferred fortran compiler by changing the
'FC' variable in the Makefile.
**************************************************************
INPUT
Input consists of the number of elements, their names and sto-
ichiometry, and the energy of the compound of interest, and
all the competing phases. Input can be read from an input file
(called input.dat - there is an example file provided, copy
SAMPLE_INPUT to input.dat to try it out) or can
be entered interactively. The name of the element whose chemi-
cal potential is to be set as the dependent variable must be
inputted also.
The format for entering a compound is -
N
n_a A n_b B n_c C ... E1
where N is the total number of elements, n_a is the number of
type A elements etc., and E1 is the energy.
Beware - it is possible to not set a dependent variable. If
this is the case, the code will still run. However, only the
intersection points with the compound of interest itself are
actual solutions. It is advisable to always set a dependent
variable.
**************************************************************
OUTPUT
Output is found in the file results.dat. The limiting inequal-
ities that apply to the system are given first. Then (if the
system is stable) the intersection points (including the value
of the dependent variable at each point) are given. These con-
sist of the corner points of the stability region in the che-
mical potential space. Next is given a list of each competing
phase, giving its corresponding equation in terms of the inde-
pendent variables, and the intersection points relevant to
that phase. The compound of interest itself is given last.
The user will be asked whether they want a grid of points in
the stability region printed. If so, they must enter the dens-
ity of the grid (in terms of the chemical potential values).
If the system is 2D or 3D, a file 2Dplot.dat (or 3Dplot.dat)
will be created. The contents of this file may be pasted in-
to a Mathematica notebook, where the stability region in the
chemical potential space can be visualised. A file 2Dplot.plt
(or 3Dplot.plt) will also be produced, which can be loaded
directly into gnuplot. Finally, for 2D systems, a file
2Dplot.txt is created which contains line points so that the
lines corresponding to compounds can be plotted using
whichever plotting software is preferred.
For binary systems, the line segment that corresponds to the
stability region in the 1D chemical potential space is given.
The equation governing the constraint on the two chemical po-
tentials is also given, so that the value of the dependent
variable can be worked out easily.
**************************************************************
RESTART
It is possible to restart from a previous run. To do this,
copy result.dat to restart.dat and re-run. There are 3 options
available on restart -
(a) Change the dependent variable
(b) Add more competing phases
(c) Set a chemical potential to a particular value
Option (a) is self-explanatory. For option (b), the additional
competing phases can be inputted via a file extra_phases.dat,
which uses the same format for data input as input.dat (there
is an example provided - just copy SAMPLE_EXTRA_PHASES to
extra_phases.dat), or interactively (if extra_phases.dat
does not exist). Option (c) is not available if the system is
binary - this is because the solution is trivial. Just use the
equation governing the constraint in the results.dat file.
**************************************************************
Any bugs or problems - please email j.buckeridge@lsbu.ac.uk
**************************************************************